Re: 45 HP Commercial Jonson

I did some looking at the online parts catalogs.Electric start models were only listed for 89-92.The air silencer was different between the rope start and electric start models.Looking at parts prices the rope start silencer which was used for many years on the 45RC is more expensive and the shape makes me think it is the metal silencer. The plastic silencer used on electric start models looks more square and is probably plastic. Yours could have been a rope start model with a dealer installed starter. Bill is the expert on these since he was turning wrenches back then.I couldn't cross reference gearcase but across the years the water pump impeller showed 35 - 55 hp. They may have used the 2 cylinder water pump on the 60/70/75 gearcase.

Re: 45 HP Commercial Jonson

Mine is electric and rope start. I removed the lower unit and will pull the impeller - hoping to find some part numbers on the impeller. Also I’ll find out the gear ratio which may shed some light on things.

Re: 45 HP Commercial Jonson

I pulled the lower unit and took receipt of a 1992 owners manaul for 40 through 55 hp OMC's. Looks to be the 12:32 gear set in the 70 hp lower unit howsing. Glad I purchased a used OMC service manual - it's great.